Microwave systems require the ability to actively redirect signal flow as desired for operational mode. For example, a broad band radio system often requires several antennas to cover the entire band of operation, while a single power amplifier can cover this operational bandwidth. Consequently, it is necessary to direct the high power amplifier signal to the required antenna structure, depending on the transmission frequency of the radio.
Handling high power RF and microwave signals requires switching devices that can operate reliably at high peak voltages. The most common approach to handle such high power levels using existing technology relies on PiN diode structures which demand high dc power for proper operation. In fact, PiN diode switches capable of handling 20 watts RF power commonly use up to 1 watt of dc power. This power consumption is a significant power burden, especially for applications requiring battery operation. In addition, due to the requirements of bias injection, PiN diode switches may be difficult to integrate, and may be limited to a reduced frequency bandwidth.
Alternatively, Gallium Arsenide (GaAs) HEMT switches, which have low dc power consumption, may not operate at high RF power levels. Switches using these devices may not be capable of handling high RF power levels due to the lower voltage handling of these devices.